A framework
The glomerulonephritides are best organised along a spectrum from nephritic (inflammatory, haematuric) to nephrotic (heavy proteinuria), though there is overlap.
Nephritic syndrome
Glomerular inflammation → haematuria (with red-cell casts), hypertension, oliguria and a rising creatinine, with modest proteinuria.
- IgA nephropathy — haematuria after an URTI
- Post-streptococcal GN — low C3, weeks after infection
- Anti-GBM disease — pulmonary-renal syndrome, linear IgG
- ANCA-associated vasculitis — pauci-immune crescentic GN
- Membranoproliferative GN — low C3, "tram-track" GBM
- Lupus nephritis — low complement, "full-house" immunofluorescence
Nephrotic syndrome
A leaky filtration barrier → proteinuria (>3.5 g/day), hypoalbuminaemia, oedema and hyperlipidaemia, with little inflammation.
- Minimal change disease — commonest in children, steroid-responsive
- Focal segmental glomerulosclerosis — commoner in adults; HIV, obesity
- Membranous nephropathy — anti-PLA2R; older adults
- Diabetic nephropathy and amyloidosis — systemic causes
Investigating a glomerulonephritis
- Urinalysis/microscopy — blood, protein and casts distinguish nephritic from nephrotic patterns
- Immunological screen — complement, ANA/anti-dsDNA, ANCA, anti-GBM, immunoglobulins and electrophoresis, hepatitis serology
- Renal biopsy for definitive diagnosis in most adults
MRCP-specific traps
- Red-cell casts signify a nephritic (glomerular) process.
- A low complement (C3) narrows the differential (post-strep, MPGN, lupus, cryoglobulinaemia).
- Nephrotic syndrome carries a high thrombosis risk (notably in membranous disease).
Summary
Classify glomerulonephritis along the nephritic (haematuria, casts, hypertension) to nephrotic (heavy proteinuria, oedema) spectrum. Use urinalysis, an immunological screen (including complement) and usually biopsy to reach the diagnosis, then treat the specific disease.
nephrologyglomerulonephritismrcp part 2